Substrate influence on the ordering of organic submonolayers: a comparative study of PTCDA on Ag(110) and Ag(111) using HREELS

Tautz, F. Stefan; Sloboshanin, S.; Shklover, Valery; Scholz, Reinhard; Sokołowski, M.; Schaefer, J.A.; Umbach, E.

doi:10.1016/s0169-4332(00)00450-5

Cited by 26 publications

(18 citation statements)

References 17 publications

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“…Mode A can be assigned to the metal-N stretching mode, the modes B and C are out-of-plane deformation modes of the macrocycle. Mode D and E are out-of-plane C-H stretching modes that are very characteristic for aromatic molecules (e.g., for PTCDA, see [4,[55][56][57][58]). Similar vibrational properties have also be observed for ZnPc/Ag (110) [59] and CuPc/Au(111) [60].…”

Section: Hreels Resultsmentioning

confidence: 99%

Submonolayer and multilayer growth of titaniumoxide-phthalocyanine on Ag(111)

2016

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For exploiting the full potential of organic materials for future organic electronic devices it is of crucial importance to understand structural and electronic properties of metal-organic interfaces and adsorbate systems, in particular electronic interactions and growth mechanisms. Phthalocyanine molecules represent one class of materials which are very frequently discussed in this context. They feature an appealing tunability in terms of structural, electronic and magnetic properties, simply by exchanging the central (metal) atom or group of atoms. Here we present a comprehensive study of one of the model systems in this field, TiOPc on Ag(111). We discuss structure formation and growth from submonolayer to multilayer films, based on results obtained by electron diffraction, scanning tunneling microscopy, electron energy loss spectroscopy, x-ray standing waves, photoelectron spectroscopy and pair potential calculations. Similar to related metal-phthalocyanine adsorbate systems we find three distinct phases in the submonolayer regime, a disordered gas-like 'g-phase', a commensurate 'c 2 -phase' at low temperature, and a 'p.o.l.-phase' consisting of a series of point-online structures with continuously shrinking unit cells. For the latter a uniform TiO-up configuration (Ti-O group pointing towards vacuum) was found. Hence, the first-layer molecules form a strong dipole layer, the dipole moment of which is compensated by molecules adsorbing in the second layer at hollow-sites in TiO-down geometry (Ti-O group pointing towards the surface). The Coulomb interaction between the dipole moments in the first and second layer stabilizes this bilayer structure and causes a bilayer-by-bilayer growth mode of molecular films above a thickness of 2ML. We report the structural properties (vertical adsorption heights, inter-layer distances, inplane orientations and positions) of the molecules in all phases in detail, and discuss the effect of inelastic dynamical charge transfer. Our results contribute to a comprehensive understanding of this interesting adsorbate system and, in comparison with earlier studies on CuPc, H 2 Pc and SnPc on Ag(111), we shine new light on the interesting interplay of molecule-molecule and molecule-substrate interactions.

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Section: Hreels Resultsmentioning

confidence: 99%

Submonolayer and multilayer growth of titaniumoxide-phthalocyanine on Ag(111)

2016

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“…NEXAFS is sensitive to the adsorption angle α of a specifi c molecular moiety (as defi ned the ordering of the fi rst monolayers depends strongly on the underlying substrate but for thick enough multilayer fi lms, a bulk-like structure prevails. [ 22 , 23 ] For molecules with stronger intermolecular forces due to functional groups like perylenetetracarboxylic-dianhydride [ 24 ] or biphenyl-oxalic amide, [ 25 ] the transition to the bulk ordering takes place even faster. The use of strongly corrugated substrates such as Cu(110) and its oxygen-covered variant allowed controlling the azimuthal alignment of sexithiophene [ 26 ] and the afore mentioned sexiphenyl, [ 9 ] but in both cases only minor changes to the bulk-like ordering could be achieved in the thin fi lms.…”

Section: Introductionmentioning

confidence: 99%

Uniform π‐System Alignment in Thin Films of Template‐Grown Dicarbonitrile‐Oligophenyls

Klappenberger

Kühne

Marschall

et al. 2011

Adv Funct Materials

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The ordering and conformational properties of dicarbonitrile‐para‐oligophenyls are studied with complementary methods, namely X‐ray structure analysis, low‐temperature scanning tunneling microscopy, and near‐edge X‐ray absorption fine‐structure spectroscopy. The packing of the functionalized variants differs from their technologically interesting para‐oligophenyl counterparts, both in the bulk crystal phase and in thin films grown by organic molecular beam epitaxy (OMBE) under ultra‐high vacuum conditions on the Ag(111) surface. In the crystal phase, the conformation depends on the number n of phenyl rings, exhibiting an intriguing screw‐like structure in the case of n = 4 at room temperature as well as at 180 K. For OMBE‐grown thin films, the whole series acquires the same type of conformation, characterized by alternately twisted phenyl rings, similar to the pure oligophenyl species. However, for all tested molecules, the orientation of the molecular reference plane is uniform within the entire film and coincides with the surface plane. This contrasts with the herringbone ordering adopted by the phenyl backbones without the carbonitrile groups. Our results demonstrate how the functionalization of moieties with extended conjugated electron systems can help to improve the structural homogeneity in technologically relevant organic thin films.

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“…We note that several publications address the adsorption of PTCDA on Ag [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] or other surfaces [2,[19][20][21][22][23][24][25], and also similar molecules have been investigated as adsorbates [1,2,7,20,[26][27][28][29][30][31][32][33]. Here, we concentrate on the chemical bonding and on electronic interface states using several complementary high-resolution techniques.…”

Section: Introductionmentioning

confidence: 99%